Retarding Effect Research Articles

Facile alteration of the molecular structure of phosphonamide for efficient flame retardancy in TPU

In this work, three phosphonamide flame retardants with different chain segment structures (PPP, PPDA, EDP) were designed and synthesized, and efficient flame-retardant TPU systems were obtained by comparing the flame-retardant effects of three phosphonamide flame retardants in TPU. First, it was found that phosphonamide flame retardants containing p-phenylenediamine groups in the chain segment structure had better flame retardant effects than those containing piperazine groups. This was reflected in the experiment that the TPU/9%PPP only achieved UL 94 V-2 rating, but TPU/9%PPDA successfully passed the V-0 test. Then, EDP was obtained by further replacing the phenyl in PPDA with ethoxy and p-phenylenediamine group retained, which had the highest flame-retardant efficiency among all phosphonamide flame retardants. Its limited oxygen index (LOI) value exceeded 30 %, higher than that of TPU/9%PPDA (27.8 %), and achieved anti-melt dripping during UL-94 test. The LOI value of TPU/9%EDP was increased by 36 %, while the peak heat release rate and total heat release were significantly reduced by 77 % and 52 %, respectively, compared with pure TPU. Based on the analysis of char residue, EDP formed a protective char layer at the earliest time, playing a barrier protection role. This work provides a pathway for efficient flame retardant TPU. Also, the design idea of phosphonamide flame retardants is a useful reference for the preparation of multifunctional flame retardants.

Differential roles of Cassia tora 1-deoxy-D-xylulose-5-phosphate synthase and 1-deoxy-D-xylulose-5-phosphate reductoisomerase in trade-off between plant growth and drought tolerance

Due to global climate change, drought is emerging as a major threat to plant growth and agricultural productivity. Abscisic acid (ABA) has been implicated in plant drought tolerance, however, its retarding effects on plant growth cannot be ignored. The reactions catalyzed by 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) proteins are critical steps within the isoprenoid biosynthesis in plants. Here, five DXS (CtDXS1-5) and two DXR (CtDXR1-2) genes were identified from Cassia tora genome. Based on multiple assays including the phylogeny, cis-acting element, expression pattern, and subcellular localization, CtDXS1 and CtDXR1 genes might be potential candidates controlling the isoprenoid biosynthesis. Intriguingly, CtDXS1 transgenic plants resulted in drought tolerance but retardant growth, while CtDXR1 transgenic plants exhibited both enhanced drought tolerance and increased growth. By comparison of β-carotene, chlorophyll, abscisic acid (ABA) and gibberellin 3 (GA3) contents in wild-type and transgenic plants, the absolute contents and (or) altered GA3/ABA levels were suggested to be responsible for the balance between drought tolerance and plant growth. The transcriptome of CtDXR1 transgenic plants suggested that the transcript levels of key genes, such as DXS, 9-cis-epoxycarotenoid dioxygenases (NCED), ent-kaurene synthase (KS) and etc, involved with chlorophyll, β-carotene, ABA and GA3 biosynthesis were induced and their contents increased accordingly. Collectively, the trade-off effect induced by CtDXR1 was associated with redesigning architecture in phytohormone homeostasis and thus was highlighted for future breeding purposes.

Core-shell flame retardants based on Chitosan@MMT coated ammonia polyphosphate for enhancing flame retardancy of polyurethane

In this manuscript, the core-shell flame retardants based on chitosan@MMT coated ammonia polyphosphate (APP@CS@MMT) was prepared and then incorporated into the TPU matrix. Through analyzing the effects of the flame retardant on the property reinforcements, it’s found that TPU/APP@CS@MMT composites have the excellent flame retardant and smoke suppression performance. The pHRR, THR, pSPR and TSP of TPU/APP@CS@MMT composites were remarkably decreased by 62.58%, 71.56%, 90.43%, 83.22%, and 93.60%, respectively. Furthermore, the mass of residual chars increased significantly from 0.85% for pure TPU to 21.95% for TPU/APP@CS@MMT composites. The TPU/APP@CS@MMT composites can improve both the flame-retardant and smoke suppression performances of TPU. Through the thermogravimetric test, cone calorimetry test, and char structure analysis, the flame retardant mechanism of the TPU/ APP@CS@MMT composites was also investigated. The APP@CS@MMT mainly plays its flame retardant role in the condensed phase. This work also provides a green and facile methodology for creating flame retardant TPU and helps broaden the TPU’s practical application in industry.

Heat and Mass Transfer On MHD Flow Problems with Hall and Ion Slip Effects On Exponentially Accelerated Plate

We in this paper intended to investigate heat and mass transfer for MHD free convective flow for exponentially accelerated plate. The effects of Ion slip and Hall are studied considering variable temperatures, concentration, and angle of inclination. We applied finite element analysis for solving governing equations. Flow velocity, concentration and temperature’s graphical profiles are examined for non-dimensional parameters. Flow reversal is prevented due to magnetic field, is observed. Velocity experiences retarding effect due to angle of inclination, this helps in acknowledging drag force in seepage flow.

Screened plasmons of graphene near a perfect electric conductor

Screened plasmon properties of graphene near a perfect electric conductor (PEC) are investigated taking into account the retardation effects. A detailed discussion of the dispersion relation of the mentioned screened plasmonic waves is presented and illustrated graphically using classical electrodynamics and a linearized hydrodynamic model that includes Fermi correction. The result indicates that for realistic wavenumbers, the dispersion relation of plasmonic waves of isolated graphene is almost unaffected by the Fermi correction, while this correction is an important factor for the screened plasmons of graphene near a PEC, where it increases the frequency of surface waves. The results show that near the graphene neutrality point, the surface wave has linear dispersion with a universal speed close to vF/2. Such linear dispersion for surface waves (also known as energy waves) appears to be a common occurrence when splitting of plasma frequencies occurs, e.g., in the electron–hole plasma of graphene [Zhao et al., Nature 614, 688 (2023)]. Furthermore, analytical expressions for the energy parameters (the power flow, energy density, and energy velocity) of screened plasmons of the system are derived. Also, the analytical expressions are derived and analyzed for the damping function and surface plasmon and electromagnetic field strength functions of surface waves of the system with small intrinsic damping.

Assessment of Cytogenotoxicity of Plastic Industrial Effluent Using Allium cepa Root Tip Cells.

The effects of plastic effluent in Kano Metropolis on cytotoxicity and genotoxicity were examined using a test on Allium cepa root cells. The physicochemical characteristics of industrial wastewater were assessed, and the results showed values that were higher than the required criteria; this implies that the effluent was not treated before to disposal. For 96 hours, a group of 40 onion bulbs was cultivated in various concentrations of plastic effluent: 15, 30, 45, and 60% (v/v). The control was made up of distilled water. Following 96 hours, the four treated root tips from each replication's bulbs were harvested and subjected to the acetoorcein squash technique for cytogenetic analysis. High concentrations of the industrial effluents had severe development retarding effects on the root tips. Root growth was inhibited with EC50 values of 48% after treatment with the effluents in comparison to control. When Allium cepa was exposed to different quantities of plastic effluent, the results of an analysis of variance (ANOVA) showed that the mean root length varied, and this variation was statistically significant (p < 0.05). With rising effluent concentrations, the mitotic index (M.I.) rapidly dropped. Chromosomal abnormalities were caused by the plastic effluent in the root cells of Allium cepa, especially sticky chromosome and binucleated cells being the most frequently seen at lower concentrations of 15%. It was discovered that the compounds found in plastic wastewater could injure live beings as well as harm the environment if not treated. Legal mechanisms must be used to push businesses and manufacturers to switch to environmentally friendly technologies.

A ternary polymer flame retardant and its synergistic flame retardant effect with piperazine pyrophosphate in EP

A ternary polymer flame retardant and its synergistic flame retardant effect with piperazine pyrophosphate in EP

A Comparative Investigation of Random Forest Regression and Artificial Neural Networks for Predicting Crack Growth Life of a Fighter Aircraft Wing Joint Under Spectrum Loading

Estimating fatigue life is challenging due to the input parameters’ statistical natures, such as the manufacturing process, scatter of service loads, microstructure, etc. Regarding fatigue life calculation in the aerospace industry, the importance of an accurate estimation becomes more critical due to strict safety, certification, service costs, and competitiveness regulations. The ability of soft computing methods to reveal complex relationships between multiple parameters and their computational speed could help predict fatigue life, especially in the service. This study compares random forest regression and artificial neural network methods to estimate the crack growth life of a fighter jet aircraft wing joint in terms of their computational time and accuracy. In addition, permutation feature importance and hyper parameter optimisation studies are conducted to extract essential features, investigate their effects on estimation performance, and fine-tune model parameters. The analysed joint is made of 7050-T7451 aluminium, widely used as a structural element in the aerospace industry. Since a hole is one of the major sources of stress concentration, and there may be many holes involved in any engineering structure, it is reasonable to assume that fatigue cracks may initiate at some of these holes during the service life of engineering structures. The crack type considered is a thru-crack around a hole, which is more severe than a corner crack. Load spectra are derived using the Fighter Aircraft Loading Standard for Fatigue (FALSTAFF) to calculate crack growth life. Considering particular service load conditions, ninety different spectra are developed, and the crack growth life of the joint is calculated based on linear elastic fracture mechanics correspondingly. Also, to simulate the worst-case scenario, friction between members and the retardation effect of load spectra are not considered when calculating crack growth life. Python’s Tensor Flow and Scikit-learn libraries are utilised to build machine learning models......

Eliminating scale effect: Development and attenuation of coal spontaneous combustion

Low temperature oxidation can occur in coal and coal piles, which can lead to severe fires in coal fields, storage rooms, and goaf areas. An important feature of these coal fire disasters is their large scale, providing a favorable environment for the inoculation of coal fires. A new method for studying coal oxidation reactions, which combines theoretical analysis with multi physical field numerical models, has been proposed to eliminate the influence of scale effects. Based on the theoretical analysis, the reliable numerical simulation conditions are obtained, and the results are compared with those of large coal spontaneous combustion experiment. The temperature, gas and reaction rate of coal oxidation have been analyzed and verified. The attenuation characteristics of coal oxidation reaction under sealed and nitrogen retarding measures have also been analyzed with emphasis. The research results indicate that the proposed new simulation method has been proven to be effective through multiple results validation. Sealing measures can weaken coal oxidation reactions, but heat elimination is slower. The measure of injecting nitrogen can quickly control local coal oxidation reactions and remove heat. The greater the flow rate of inert gas, the better the retarding effect on coal. The development process of coal oxidation will form “quasi spherical” and “crescent shaped”, which are prominent characteristics of slow oxidation and rapid propagation, respectively.

Mixed Convection of Cu–H2O Nanofluid in a Darcy–Forchheimer Porous Medium Microchannel with Thermal Radiation and Convective Heating

Heat transfer and convective flow of Cu–H2O nanofluid in a microchannel with thermal radiation has many attributes in engineering, industries, and biomedical sciences including cooling of electronics, drug delivery, cancer therapy, optics, missiles, satellites, and lubricants. Therefore, this paper aims to investigate the hydrodynamical behaviors and heat transfer characteristics of Cu–H2O nanofluid through a porous medium microchannel with thermal radiation and convective heating. The highly non-linear partial differential equations that govern the momentum and energy equations are formulated, non-dimensionalized, transformed into ordinary differential equations and solved numerically via the fourth order Runge-Kutta integration scheme. Consequently, the numerical simulation reveals that the nanofluid velocity and temperature profiles show a rising pattern with increasing values of the pressure gradient parameter, variable viscosity parameter, Darcy number, thermal Grashof number and Eckert number. The temperature profile escalates with the Prandtl number however it diminishes with the Biot number, Forchheimer number, suction/injection Reynolds number and nanoparticles volume fraction. Furthermore, the thermal radiation parameter indicates a retarding effect on the temperature profile and hence, radiation quite effectively controls the microchannel temperature distribution which plays a significant role in cooling the flow transport system. The skin friction coefficient at both microchannel walls indicates a rising pattern with the suction/injection Reynolds number, thermal Grashof number, Eckert number and Darcy number. Moreover, at both microchannel walls the heat transfer rate enhances for large values of the suction/injection Reynolds number, thermal Grashof number, Eckert number, variable viscosity parameter and Darcy number whereas it decreases with the thermal radiation parameter, Forchheimer number and nanoparticles volume fraction. The Biot number reveals an opposite effect on the heat transfer rate at the left and right walls of the microvhannel.

Combined Triazole Disinfectants and Their Influence on the Growth and Development of Spring Wheat Seedlings

Seed treatment with fungicides is a crucial link in the plant protection system, and systemic drugs give the best effect. Therefore, it is very important to develop scientific foundations for the preparation of complex preparations with a low rate of consumption of the active substance and the inclusion of plant growth regulators that enhance growth processes and the yield of the main crop. In recent years, the directions of modification of known and practiced fungicides by various methods, including methods of mechanochemistry, have been promising. The problem of creating both new substances and their effective formulations remains urgent. Taking into account the prospects and high efficiency of triazole fungicides in the system of complex plant protection, the creation of multicomponent seed protectants of grain crops is proposed. The purpose of this study was to develop preparations based on tebuconazole (TBC) and propiconazole (PPC) in the form of solid dispersions (SD) and to study their biological activity on spring wheat plants in the conditions of the Trans-Urals. At the same time, the retardant effect of these triazoles was also studied with the help of the domestic growth regulator Floroxan. The use of new preparations on spring wheat made it possible to reduce the damage to the culture by root rot by 85–87%, productive bushiness increased by 6–11% compared to the control without treatment. A reliable increase in crop yield of 2.2 c/ha or 14% was obtained using preparation 2 (TD of the composition TBC : PPC : AG : silica = 1 : 1 : 7 : 1 + Phloroxane when the polysaccharide (AG) and the auxiliary substance of silica are included in the composition). The inclusion of the growth regulator Floroxan in the composition of the mordant mixture reduced the antioxidant effect of tebuconazole and stimulated the growth and development of wheat seedlings. It was proved that such a biological effect was achieved in conditions of drought of varying intensity during the growing season of 2021–2022.

Effects of fly ash and intumescent flame retardant on thermal, burning, and mechanical properties of polyethylene composites

In this study, fly ash (FA) which mainly consists of SiO2, Al2O3, Fe2O3, MgO, and CaO, was used as a synergistic additive (1–5 wt %) to improve the effectiveness of an intumescent flame retardant (IFR) system (25 wt %) in high density polyethylene (HDPE). IFR system composed of ammonium polyphosphate and pentaerythritol (3/1 ratio), and different amounts of FA were incorporated homogeneously into HDPE. Thermogravimetric analyses and thermal conductivity measurements were performed to determine the thermal properties. Meanwhile, limiting oxygen index, UL 94 vertical burning, and cone calorimetry tests were performed to investigate the fire resistance. Furthermore, the effects of IFR/FA additions on the mechanical properties were determined. The experimental results showed that IFR and IFR/FA additions resulted in early degradation with lower rates, and the residual mass values increased due to the char layers and the FA content. Also, IFR addition increased the thermal conductivity coefficient from 0.451 W/mK to 0.462 W/mK and IFR/FA additions further increased the coefficient up to 0.506 W/mK. Although the sample included only 25 wt % IFR could meet the requirements of UL 94 V-2 with a LOI value of 25.0%, 2, 3 and 4 wt % FA additions satisfied the criteria of UL 94 V-0 with a LOI value of 26.6%. In addition, the cone calorimeter results revealed that the peak heat release rates and total heat released values decreased with IFR (25 wt %) and FA (2, 3, and 4 wt %) additions. Furthermore, CO, CO2, and soot emissions of the composites significantly reduced with respect to HDPE. The NO increased with IFR additions due to the nitrogen content of APP. 25% IFR addition caused decreases in the tensile strength, tensile modulus, and Izod impact strength. However, FA additions slightly enhanced the mechanical properties of HDPE/IFR composite.

THERMAL DECOMPOSITION OF MONO- AND DIETHANOLAMINEBORATE MODIFIED WOOD IN AIR ATMOSPHERE

"For cellulosic materials used in various branches of the economy, the issue of increasing thermal stability is still relevant today. Especially acute is the problem of fire resistance for wood materials used in building structures. In our work, we investigated the effect of mono- and diethanolamine borates on the thermal decomposition of wood in an air atmosphere. It has been previously found that mono- and diethanolaminoborates, when used as surface modifiers, provide 100% biostability to plant raw materials. In this regard, the purpose of the study was to identify the flame retardant effect of the described modifiers. In the course of the study, it was found that the developed compositions, the main components of which are boron-nitrogen compounds, effectively reduce the combustibility of wood materials, suppress smoldering, and reduce the burning rate of wood. Since it is the smoldering of wood after the liquidation of the fire that is the main cause of structural collapse, which prevents evacuation during the fire, the use of the developed compositions for fire protection of wooden structures is extremely appropriate. A regression model of the dependence of activation energy on conversion has been obtained and substantiated on the basis of correlation and regression analysis. The presented semi-logarithmic model can be further applied to predict the dependence of the activation energy value of the thermal decomposition process of modified wood on the degree of conversion."

Corrosion Behaviors of Ni–Cr Alloys in O2, H2O and H2O + O2 Gases at 700°C and the Effect of Temperature

Pure nickel and four binary Ni–Cr (5, 10, 20 and 30 wt%) alloys were exposed to Ar–20O2, Ar–20O2–20H2O and Ar–20H2O (vol.%) at 700°C. In dry and wet O2, three Ni–Cr alloys (5, 10 and 20 wt%) formed a three-layered structure: an external NiO layer, an inner oxide layer of NiO + Cr2O3 and an internal oxidation zone (IOZ) with Cr2O3 dispersed. The Ni–30Cr alloy formed a continuous chromia layer, with locally outer NiO islands. In pure water vapor, all alloys underwent internal oxidation, nickel metal expulsion and NiO formation. Compared with the results at 650°C, increasing the temperature to 700°C did not alter the morphology of the oxide scale, but enhanced the scale growth kinetics. A significant difference between these two temperatures was that the strong retarding effect of water vapor on NiO formation in oxygen at 650°C became insignificant at 700°C. However, in water vapor only condition, NiO formation remained much slower at both temperatures. The effects of water vapor and oxygen partial pressure on NiO formation of different alloys and the effect of temperature on scale growth kinetics and morphology were discussed.

ЭФФЕКТИВНОСТЬ ОГНЕЗАЩИТНЫХ ПРОПИТОЧНЫХ СОСТАВОВ ДЛЯ ДЕРЕВЯННЫХ КОНСТРУКЦИЙ

The article considers the results of evaluating the flame retardant effectiveness of various flame retardants by the method of fire exposure according to GOST 53292–2009 and by methods of thermal analysis (thermogravimetry, differential thermogravimetry, derivative thermal analysis). According to the results of fire of surface application of flame retardants from 350 to 550 kg/m2, group I or II of flame retardant&#x0D; efficiency is provided (mass loss from 8,67 to 25 %). It is shown that the group of flame-retardant effectiveness does not actually reflect the nature and degree of realization of the mechanism of flame retardant action of flame retardants, their ability to influence the features of thermal transformations of wood. It has been established that the type of flame retardant, its chemical component composition and the mechanism of flame retardant action to varying degrees affect the main stages of thermal oxidative decomposition of wood. The results obtained can be used to evaluate the effectiveness of fire protection in reducing the intensity of the charring process and predicting the intensity of smoldering (flameless) combustion of wood. tests, it was found that with the consumption

Pyrolysis of Pine Wood in the Presence of Boron-Nitrogen Compounds.

The actuality of this research is determined by the intensification of new ways of processing woody biomass. This requires revealing the impact of various physicochemical factors on the thermal degradation of wood biopolymers. Boron-nitrogen surface modifiers are used for wood antisepsis and we decided to check their effect on flammability. The aim of the research was to evaluate the flame retardant effect of boron-nitrogen surface modifiers of wood in an inert atmosphere (nitrogen was used). The evaluation was carried out by thermal analysis of modified and the control pine wood samples. The thermal analysis included thermogravimetry, differential scanning calorimetry and kinetic parameters of thermal degradation. It was found that the flame retardant effect of boron-nitrogen wood surface modifiers was not significantly pronounced in the nitrogen atmosphere. The mechanism of the flame retardant effect of boron-nitrogen compounds is reduced to "shielding" of the surface and increasing the proportion of carbonized residue. On the basis of correlation-regression analysis of kinetic parameters of wood thermodestruction in a nitrogen atmosphere, mathematical models of activation energy dependence on conversion were obtained and substantiated. The developed models can be further applied to calculate the predicted value of wood activation energy in the nitrogen atmosphere at any conversion value.

Retardation of Aβ42 fibril formation by apolipoprotein A-I and recombinant HDL particles

The double nucleation mechanism of amyloid β (Aβ) peptide aggregation is retained from buffer to cerebrospinal fluid (CSF) but with reduced rate of all microscopic processes. Here, we used a bottom-up approach to identify retarding factors in CSF. We investigated the Aβ42 fibril formation as a function of time in the absence and presence of apolipoprotein A-I (ApoA-I), recombinant high-density lipoprotein (rHDL) particles, or lipid vesicles. A retardation was observed in the presence of ApoA-I or rHDL particles, most pronounced with ApoA-I, but not with lipid vesicles. Global kinetic analysis implies that rHDL interferes with secondary nucleation. The effect of ApoA-I could best be described as an interference with secondary and to a smaller extent primary nucleation. Using surface plasmon resonance and microfluidics diffusional sizing analyses, we find that both rHDL and ApoA-I interact with Aβ42 fibrils but not Aβ42 monomer, thus the effect on kinetics seems to involve interference with the catalytic surface for secondary nucleation. The Aβ42 fibrils were imaged using cryogenic-electron microscopy and found to be longer when formed in the presence of ApoA-I or rHDL, compared to formation in buffer. A retarding effect, as observed in CSF, could be replicated using a simpler system, from key components present in CSF but purified from a CSF-free host. However, the effect of CSF is stronger implying the presence of additional retarding factors.

Novel application of potassium methylsiliconate in cement-based materials: Retarding of hydration process and improvement of compressive strength

The presented research investigates the application of the organosilicon compound named potassium methylsiliconate (MESI) as a set-retarding admixture for cement-based materials which also provides the strengthening effect. The study concerns the impact of three dosages of MESI (1%, 2% and 3% per cement mass) on the properties of the cement paste, mortar and concrete. The greatest delay of the setting time of cement CEM I 42.5 R and retardation effect, examined by manual Vicat apparatus, was observed for addition of 1% methylsiliconate. The beginning of the setting was prolonged to 23 h. The influence of potassium methylsiliconate on the kinetics of cement hydration was investigated by isothermal calorimetry. The calorimetric results disclosed significant extension of induction period during Portland cement hydration with addition of potassium methylsiliconate as an admixture. It is especially visible in case of addition of 1% of MESI. Moreover, tests performed at 30 °C, 40 °C and 50 °C showed that MESI can also delay the cement hydration at higher temperatures. The influence of potassium methylsiliconate on the compressive strength of cement mortar and concrete after 1, 2, 7, 28 days and72 days was also investigated. In the first days of hydration, the compressive strength of the materials was reduced, but after 28 days of curing the compressive strength was increased by 21% and 16% for cement mortar and concrete, respectively. The impact of MESI on the microstructure and pore size distribution of cement pastes in 2nd, 7th and 28th of hydration was examined by mercury intrusion porosimetry (MIP). The result showed significant delay in the development of the cement pastes microstructure during the first days of hydration. The XRD and DTA/TG analysis provided the knowledge about impact of siliconate on the composition and formation of the cement phases. Both, the XRD and DTGA/TG analyze showed noticeable changes in portlandite formation during the first days of hydration. The conducted research and obtained results reveal the innovative and novel application of potassium methylsiliconate as retarders, which prolongs the workability of fresh mixture and improves the compressive strength of matured concrete and mortar. This admixtures can be a competitive alternative to traditional retarders.

Nonequilibrium Fractional Josephson Effect.

Josephson tunnel junctions exhibit a supercurrent typically proportional to the sine of the superconducting phase difference ϕ. In general, a term proportional to cos(ϕ) is also present, alongside microscopic electronic retardation effects. We show that voltage pulses sharply varying in time prompt a significant impact of the cos(ϕ) term. Its interplay with the sin(ϕ) term results in a nonequilibrium fractional Josephson effect (NFJE) ∼sin(ϕ/2) in the presence of bound states close to zero frequency. Our microscopic analysis reveals that the interference of nonequilibrium virtual quasiparticle excitations is responsible for this phenomenon. We also analyze this phenomenon for topological Josephson junctions with Majorana bound states. Remarkably, the NFJE is independent of the ground state fermion parity unlike its equilibrium counterpart.

Phase field modeling of freezing characteristics of saturated soil with different particle sizes

The unfrozen water content and its distribution are of importance to the macro mechanical behaviors of frozen soil. In this study, the phase field method was used to deeply investigate and model the evolution of the microstructure of different saturated soils during the freezing process. Particle size distribution and freezing point depression were considered in the simulation of freezing of the soil. The soil freezing characteristic curves of the soil with different particle sizes were well predicted by the phase field method. Moreover, the unidirectional freezing test was used to validate the proposed method. The simulation results successfully predicted the inhibition effect of soil particles on the spread of pore ice during the cooling process. A series of mesoscale characteristics can be well simulated, such as unfrozen water film, retardation effect of soil particles, nonhomogeneous freezing front, and isolated ice and unfrozen water. Our results provide a deeper insight into the freezing process of porous media, including the formation of pore ice, and the movement of the freezing front on a mesoscale.